1. Field of the Invention
The invention relates to a high frequency (HF) power source and a plasma generator, and more particularly improvements of an apparatus for generating high frequency electric power necessary for plasma generation and an apparatus to which it was applied.
2. Description of the Related Art
With the requirement that the Large Scale Integrated circuits (LSIs) should be integrated into larger scale and higher density integration, a RF (radio frequency) sputtering apparatus, a plasma CVD apparatus, a dry etching apparatus, ashing apparatus and so forth are used for deposition and procession of thin films in manufacturing LSIs, liquid crystal displays, etc. For any of these apparatus, plasma is
In such plasma-based systems, HF power supplies of, e,g,, a few hundred Khz to a few Ghz are used. RF frequencies, RF electric power (or electricity) ranging from a few ten watts to a few kilowatts is supplied the electrodes for plasma generation by amplifying a sine wave of a prescribed frequency by means of solid state devices or electron tubes,
Further, in the range of microwaves, microwave electricity on the order of Ghz is generated by supplying low frequency or DC electricity to a klystron or a magnetron and is supplied to the electrodes for plasma generation. However, HF or microwave electric power supplied to those electrodes is not always
According to the related art of the invention, an HF power source of a CVD (chemical vapor deposition) system for processing a semiconductor wafer 8 by means plasma, as shown in FIG. 1, comprises a crystal oscillator 1, an HF amplifier 2, a power detector 3, a matching circuit 4 and a power detecting meter 6.
The power source functions as follows. The crystal oscillator 1 generates an HF signal with a frequency of 13.56 Mhz, which is amplified by the HF amplifier 2. The resultant HF electricity is supplied via the power detector 3 and the matching circuit 4 to between electrodes 5A and 5B that are provided within a vacuum chamber 7 where a wafer 8 is processed by means of plasma.
In order to make an impedance matching between the source and the load with respect to the frequency of the HF electricity, the user adjusts variable condensers of the matching circuit 4 referring to the power detecting meter 6. The power detecting meter 6 indicates the HF electric power on the basis of the detected and reflected wave or the incident wave of the power detector 3. Thus, HF electricity is supplied to the electrodes 5A and 5B within the chamber.